Reseal

I have used CT1 here http://www.ct1ltd.com/ct1.html

Used it in my new van on top brake light, and on the sky lights on the old van three years ago and on problems whatsoever.

DO NOT use normal household Silicone as this will not last and will break down in a couple of months.

This is a non setting sealer if you need be able to break the joint again, they also have adhesive types but they are for permanent joints. I have used this, got it from CAK Tanks -
http://www.caktanks.co.uk/

"BUTYL SEALANT
SIKALASTOMER
Sikalastomer 710 butyl sealant is a high quality
non setting sealant used for a variety of joints
in caravans and motorhomes. It is especially
suitable for those situations where there is the
possibility of future disassembly, such as edge
trim on motorhomes, caravans and boats,
windows, rooflights and airvents etc. Due to its
very sticky non-setting flexibility it is ideal for
re-sealing of edge trims that have been sealed
with ordinary non-setting mastics which dry
out. Available in black, grey & white, size
300ml cartridge.
SIKA710B SIKALASTOMER-710 BUTYL SEALANT (BLACK)
SIKA710G SIKALASTOMER-710 BUTYL SEALANT (GREY)
SIKA710WSIKALASTOMER-710 BUTYL SEALANT (WHITE)"

The wee so and so's are hard to get off!

Cheers Willie.